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Title: Synthesis of polymers and copolymers of lactide through titanium initiators
Author: Martinez Velon, Maria Jose
ISNI:       0000 0001 3620 3449
Awarding Body: Aston University
Current Institution: Aston University
Date of Award: 2007
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The research described in this thesis explored the synthesis and characterisation of biocompatible and biodegradable polymers of lactide through non-toxic titanium alkoxide initiators. The research objectives focused on the preparation of polylactides in both solvent and solventless media, to produce materials with a wide range of molecular weights. The objectives of this research were also focused on the enhancement of the flexibility of the polymer chains by synthesising random and block copolymers of lactide and e-caprolactone using Ti(O-i-Pr)4 as an initiator. This work involved extensive characterisation of the synthesised copolymers using gel permeation chromatography and 1H and 13C NMR spectroscopic analysis. Kinetic studies of the ring opening polymerisation of e-caprolactone and of the copolymerisation of lactide and e-caprolactone with Ti(O-i-Pr)4 as an initiator were also carried out. The last section of this work involved the synthesis of block and star-shaped copolymers of lactide and poly(ethylene glycol) [PEG]. The preparation of lactide/PEG block copolymers was carried out by ring opening polymerisation of L-lactide using Ti(O-i-Pr)4 as an initiator and hydroxyl-terminated PEG's with different numbers of hydroxyl groups as co-initiators both in solution and solventless media. These all-in-one polymerisations yielded the synthesis of both lactide homopolymer and lactide/PEG block copolymers. In order to selectivity synthesise copolymers of lactide and PEG, the experiment was carried out in two steps. The first step consisted of the synthesis of a titanium macro-initiator by exchanging the iso-propoxide ligands by PEG with different numbers of hydroxyl groups. The second step involved the ring opening polymerisation of lactide using the titanium macrocatalyst that was prepared as an initiator. The polymerisations were carried out in a solventless media. The synthesis of lactide/PEG copolymers using polyethylene glycol with amino terminal groups was also discussed.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
Keywords: Applied Chemistry ; Chemical Engineering